Positron emission tomography (PET) is a modality of nuclear medicine for imaging metabolic processes by employing gamma photons emanated from radiopharmaceuticals ingested by a patient or injected into a patient. Multiple PET images are taken in multiple directions to generate/reconstruct a 3-dimensional PET image and/or multiple slices of a PET image. Before image reconstruction, PET raw image data are in projection/sinogram space. PET scanning generally provides useful information regarding the functional condition of the body tissues and systems such as the cardiovascular system, respiratory system, and/or other systems. PET scanning is useful for indicating the presence of soft tissue tumors or decreased blood flow to certain organs or areas of the body. Typically, a large number of PET data acquisitions (e.g., frames) are acquired at multiple bed positions during the imaging period.
Parametric PET imaging aims to image tracer kinetics over time based on dynamic data and has the potential to provide more information for tissue pathology than traditional standard uptake value (SUV) imaging. Blood input function, which characterize the concentration of radiopharmaceutical in the blood over time, is a key component in parametric PET. The blood input function can be obtained from a PET scanner using an image based method or provided by users through population based method.
A PET scanner has a limited field of view (FOV) smaller than the height of a patient's whole body. Recently, continuous bed motion (CBM) PET systems have been proposed. A CBM PET system is capable of acquiring whole body images. In CBM systems, the bed is moved with respect to the PET scanner. For example is moved from a start position, for example, head-first, to an end position, for example, the feet of a patient, at a constant rate. PET data are collected continuously from the start position to the end position.
Unlike volume images obtained by step and shoot scan, axial slices in an image obtained in a CBM scan have different time information. In CBM PET, the bed is moving while data are acquired, so the data from every axial slice are acquired at different time relative to injection, and kinematic components of the uptake model may be affected. If bed motion effects are not accounted for properly, this may cause image non-uniformity and incorrect quantification to occur. This increases the complexity of CBM PET image processing.